1. Field of the Invention
The present invention relates to a fingerprint recognition device. More particularly, the present invention relates to a device for authenticating a person by the person's fingerprints which is applicable to a desk-top type, lap-top type or note type information processor, for example, applicable to various information processors such as a personal computer, cellular phone and so forth.
It is well known that a person can be very accurately recognized by his fingerprints. On the other hand, when the fingerprints of the person are processed by a fingerprint recognition device, static electricity conducted by the person's fingers affects the fingerprint recognition device. Therefore, it is necessary to take a countermeasure for preventing the static electricity from affecting the fingerprint recognition device.
2. Description of the Related Art
In the information processor, in order to prevent a stranger from gaining access to a person's information or in order to prevent a stranger from processing information by using a person's name, there is conventionally provided a system for authenticating the person by his fingerprints. Several examples of the information processor having such fingerprint recognition function will be explained below.
Japanese Unexamined Patent Publication No. 11-185016 discloses the following information processor. In order to avoid conducting operation of turning on and off an electric power source and also in order to avoid giving a command to start collating fingerprints, when a user presses his finger against a fingerprint detecting section, a shadow formed by the finger, which has been pressed against the fingerprint detecting section, is detected by a sensor section. When it is judged that the profile of the shadow has a distribution of the shadow formed by the finger, the electric power source is turned on. After that, a fingerprint is detected from the finger, which has been pressed against the fingerprint detecting section, and collated to the fingerprint data which has been previously stored. Due to the foregoing, the detected fingerprint is distinguished, that is, the user can be distinguished. Therefore, various data which agree with the thus distinguished user can be utilized in this information processor.
Japanese Unexamined Patent Publication No. 11-175478 (EP 0923018) discloses the following person authenticating system. In order to reduce the dimension of an input device and in order to prevent a stranger from using the information processor, the information processor comprises a computer, input device and fingerprint data base. The input device includes a keyboard, fingerprint sensor integrated with the keyboard, display, adapter circuit and fingerprint collating device. Only when information of a fingerprint detected by the fingerprint sensor coincides with information of a fingerprint stored in the fingerprint data base, log-on processing and data encoding processing are conducted.
According to Japanese Unexamined Patent Publication No. 9-330140, in order to ensure security without using a troublesome password, the keyboard includes a fingerprint reading section 1, and the computer body includes a fingerprint collating section and fingerprint storing section, and data is displayed on CRT. When an operator is going to operate the computer, he presses his finger against the fingerprint reading section. The fingerprint reading section reads the fingerprint with a beam of light sent from the inside and sends the fingerprint data to the fingerprint collating section of the computer body. If the thus sent fingerprint data is recognized to be the same as fingerprint data which has already been registered, operation of log-in to the personal computer 2 can be allowed.
A mouse type input device disclosed in Japanese Unexamined Patent Publication No. 2000-194830 includes: a sensor for detecting individual body distinguishing information, arranged so as to be capable of coming into contact with the mouse from the outside; an electrode arranged at a position on the mouse easily coming into contact with the user's hand; and a means for supplying an electrical potential of the ground to the electrode. Static electricity charged to the user's body and static electricity generated when the mouse is operated can be discharged by the grounded electrode of the information processor. Therefore, it is possible to detect individual distinguishing information, the S/N ratio of which is high.
Specifically, static electricity can be discharged as follows. The electrode is arranged at a position on the mouse with which the user's hand can be easily contacted. When the user's hand comes into contact with the electrode in the case of operating the mouse, static electricity charged to the user's body can be discharged to the reference voltage (ground) on the information processor side. Accordingly, there is no possibility that malfunction is caused in the distinguishing function of the fingerprint sensor by the noise generated by static electricity. Also, there is no possibility that the function of the authenticating system itself including the fingerprint sensor is impaired.
As described above, the information processor adopting the recognition system by which the person is recognized with his fingerprint is conventionally known. According to Japanese Unexamined Patent Publication No. 2000-194830, in order to prevent the occurrence of malfunction of the fingerprint distinguishing sensor and also in order to prevent the occurrence of failure in the function of the fingerprint distinguishing sensor, there is provided a mechanism for discharging static electricity, which has been charged in the user's body, to the ground on the information processor side.
However, according to the person authenticating system disclosed in Japanese Unexamined Patent Publication No. 2000-194830, the fingerprint distinguishing sensor is provided with a cover. When this cover is opened and the user's finger is inserted into the fingerprint distinguishing sensor, the person can be authenticated. However, it is not necessarily guaranteed that the user's hand comes into contact with the electrode for discharging before the user's finger comes into contact with the distinguishing sensor. Therefore, it is necessary for the user to be aware that his hand must come into contact with the electrode for discharging before the authentication of himself. Since this fingerprint distinguishing sensor is arranged in the mouse of the information processor, it is impossible to apply this system to any portable type information processor having no mouse.